Experts at Fischer Weilheim, the German demolition company, developed a method for the deletion of thick concrete tunnel lining in a tram tunnel in Stuttgart.
To start with, the depth of nearly 5 ft (1.6 m) thick concrete walls was decreased by cutting strips and by using a Kemroc rotary drum cutter. A Kemroc cutter wheel was then aimed to cut the wall into sections at these strips. In the end, the sections were pulled out, broken down and processed.
In the first point, the excavator operator picks up a Kemroc KR 165 rotary drum cutter and grinds a 150 cm (59 in) wide vertical slot into the concrete wall.
This reduces the wall thickness to 39 in (100 cm), which is the cutting depth of a DMW 220_1000 cutter wheel.
Then, the operator picks up the tool and cuts through the wall in the just before ground slot. These two phases are then repeated for cutting horizontal slots separating the tunnel lining into different segments.
The next step is to apply a breaker to weaken the segment at the base of the wall before pulling it down using the excavator bucket. The tunnel lining wall falls to the floor. In this stage, each layer of soil, bituminous material and soil can be eliminated individually leaving a solid piece of concrete that can be broken down using shear cutter and breaker for removal from the site.
Two months after starting the job this summer, nearly half of the tunnel lining had been removed.